Vertical infantile nystagmus: Explanation of why the direction of nystagmus is vertical.

This case report presents a rare case of infantile nystagmus syndrome (INS) in which the direction of infantile nystagmus (IN) was vertical. A 66-year-old woman was referred to our department for investigation of abnormal eye movements. She showed a disordered field of view with a homonymous hemianopia in the lower left quadrant and vertical gaze-evoked nystagmus, but there were no other abnormal neurological findings. She did not complain of an oscillopsia. Imaging revealed that the cause of hemianopia was atrophy and low cerebral blood flow in the right occipital lobe. The vertical nystagmus became strong when attempting to fixate to stationary targets. A reversed optokinetic nystagmus response was observed in the vertical optokinetic nystagmus test. From these eye movements, we diagnosed her nystagmus as vertical IN. Patients with INS see everything by saccades. IN consists of the alternate appearance of saccades and preceding slow eye movements. For these eye movements, a wide visual field is necessary. In this case, vertical IN was caused by the wider vertical than horizontal visual field resulting from homonymous hemianopia. Therefore, the direction of IN is horizontal in most patients with INS because their horizontal visual field is the widest field.

Visual search in infantile nystagmus syndrome.

CLINICAL RELEVANCE: Research on infantile nystagmus syndrome (INS) and visual search is limited. Conducting this research could assist practitioners in understanding how INS affects the real-life visual activities of patients and aid in developing new clinical visual function assessments for INS. BACKGROUND: The aim of this work is to investigate how subjects with INS perform visual search tasks, and, particularly, to assess how INS subjects perform when targets are located at their null position or away from it, and when under additional cognitive demands. METHODS: INS subjects (N = 15) and controls (N = 20) performed conjunction and feature search tasks, both with and without mental arithmetic. Search performance was assessed using log-transformed total search time, gaze-dependent search time, and accuracy. Cognitive demand was quantified by pupil size and the NASA task-load index score. RESULTS: INS subjects showed longer search times compared to controls in conjunction search (P < 0.01), but not in feature search. Within INS and control subjects, the total search times were significantly increased by the addition of mental arithmetic (P < 0.0001). There was no difference in gaze-dependent search times between null target position and 15° away from null target position of subjects in conjunction search (P > 0.05). Accuracies were 100% for both control and INS subjects in both conjunction and feature search. CONCLUSION: Conjunction visual search was impaired in adult INS subjects, and further worsened under increased cognitive demand. The null position did not affect the visual search performance in INS.

Expanding SPG7 dominant optic atrophy phenotype: Infantile nystagmus and optic atrophy without spastic paraplegia.

Spastic paraplegia is a neurodegenerative disorder characterized by progressive leg weakness and spasticity due to degeneration of corticospinal axons. SPG7 encodes paraplegin, and pathogenic variants in the gene cause hereditary spastic paraplegia as an autosomal recessive trait. Various ophthalmological findings including optic atrophy, ophthalmoplegia, or nystagmus have been reported in patients with spastic paraplegia type 7. We report a 15-year-old male patient with a novel heterozygous variant, c.1224T>G:p.(Asp408Glu) in SPG7 (NM_003119.3) causing early onset isolated optic atrophy and infantile nystagmus prior to the onset of neurological symptoms. Therefore, SPG7 should be considered a cause of infantile nystagmus with optic atrophy.

Correction of horizontal and torsional compensatory head posture in infantile nystagmus syndrome using horizontal rectus muscle recession and resection with vertical transposition.

Infantile nystagmus syndrome (INS) is often characterized by an identifiable null zone. When the null zone is not in the straight-ahead gaze, a compensatory head posture (CHP) is adopted by the patient to achieve best possible vision. Various surgical procedures have been recommended to correct a CHP which is clinically predominant in one dimension of yaw (lateral rotation), pitch (anterior or posterior flexion/extension) or roll (lateral flexion). However, the presence of a complex CHP which is clinically evident in more than one dimension, warrants either a combination of multiple techniques or a stepwise approach. We report the case of a 26-year-old male with INS with an eccentric null and a multi-dimensional complex CHP of 30º left face turn, 20º right head tilt and 10º chin depression. The patient was managed by all four horizontal rectus muscle recession and resection with full tendon vertical transposition to address the face turn and head tilt. He underwent lateral rectus muscle (LR) recession with upward transposition and medial rectus muscle (MR) resection with downward transposition in the right eye. MR recession with upward transposition and LR resection with downward transposition were performed in the left eye. Postoperatively. the head posture improved significantly for both distance and near viewing. The chin depression also reduced after the procedure. He developed transient diplopia due to a small vertical deviation after the surgery, which was managed by prisms and fusional exercises. Thus, horizontal rectus muscle recession and resection combined with vertical transposition may be helpful to simultaneously improve the head tilt associated with the face turn, obviating the need for vertical rectus muscle or oblique muscle surgery.

A Preliminary Study on the Outcome of Plication Augmentation of the Augmented Anderson Procedure for Patients with Infantile Nystagmus Syndrome and a Face Turn.

PURPOSE: To report the results of plication augmentation of the augmented Anderson procedure in patients with infantile nystagmus syndrome and face turn. METHODS: In this retrospective study, all patients who underwent plication augmentation of the augmented Anderson procedure between August 2015 and November 2018 were included. Our study included patients older than 6 years with a face turn >25°. We also included patients with residual face turns ≥15° after Anderson-type procedures. The face turn was measured by a goniometer and also quantified with prisms placed with apex in the direction of the face turn. We plicated the medial rectus of one eye by 5.0 mm and lateral rectus of the fellow eye by 7.0 mm based on the direction of the face turn in addition to the augmented Anderson procedure. Patients were reviewed on the 1st postoperative day, 1st month, and every 6 months thereafter. RESULTS: Eight patients with a mean face turn of 27.5° ± 6.5° underwent plication augmentation of the augmented Anderson procedure. Two patients had residual face turns after a previous Anderson-type procedure. We obtained a mean correction of 25° ± 6.5° with a median prismatic correction of 45 prism diopters (PD) for each eye. The median face turn at the last review was 2.5°, and all patients were corrected to within 10°. Excluding patients operated for residual face turns, we had a mean dose response of 2.7 PD/mm and 1.7°/mm of surgery on each eye. Five patients had an improvement in null zone visual acuity. Two patients had a restriction in ocular motility of -2 in the direction of the recessed extraocular muscle at the last review, and the remaining had a -1 restriction. CONCLUSIONS: Plication augmentation of the augmentation Anderson procedure appears to be a safe and effective procedure for patients with infantile nystagmus syndrome and a face turn more than 25°. It may also be used for residual face turns more than 15°.

Diagnostic yield of targeted next-generation sequencing in infantile nystagmus syndrome.

Background: Infantile nystagmus syndrome (INS) is a genetically heterogeneous disorder. Identifying genetic causes of INS would help clinicians to facilitate clinical diagnosis and provide appropriate treatment. The aim of this study was to determine the diagnostic utility of targeted next-generation sequencing (NGS) for INS.Materials and methods: We recruited 37 patients who were referred to the Neuro-ophthalmology clinics for evaluations of INS. NGS was performed using a targeted panel that included 98 candidate genes associated with INS. We identified pathogenic variants according to guidelines of the American College of Medical Genetics and Genomics. We also calculated the sensitivity and specificity of each clinical sign to assess the diagnostic yield of our gene panel.Results: After variant filtering, annotation, and interpretation, the potential pathogenic variants were detected in 13 of the 37 patients, achieving a molecular diagnostic rate of 35%. The identified genes were PAX6 (n = 4), FRMD7 (n = 4), GPR143 (n = 2), CACNA1F (n = 1), CNGA3 (n = 1) and GUCY2D (n = 1). In approximately 30% (n = 4) of the patients, the initial clinical diagnosis was revised after a molecular diagnosis was performed. The presence of a family history had the highest predictive power for a molecular diagnosis (sensitivity = 61.5%, specificity = 91.7%), and the sensitivity increased when the family history was considered together with one of two clinical signs such as pendular nystagmus waveforms or anterior segment dysgenesis.Conclusions: Our study shows that targeted NGS can be useful to determine a molecular diagnosis for patients with INS. Targeted NGS also helps to confirm a clinical diagnosis in atypical phenotypes or unresolved cases.

Progress of research on infantile nystagmus syndrome / 国际眼科杂志(Guoji Yanke Zazhi)

@#Infantile nystagmus syndrome(INS)is a congenital pathological nystagmus characterized by binocular involuntary conjugative oscillation and reverse optokinetic nystagmus. This condition is often accompanied by amblyopia, strabismus, and torticollis, affecting the visual function of INS patients. As the cause of the disease is unclear and cannot be completely cured, early detection and appropriate intervention of INS should be carried out. Based on domestic and foreign researches of INS, in this paper, we summarize INS etiology and occurrence mechanism. Furthermore, to provide a reference for clinical application and future research directions of INS, we have systematically introduced the most recent INS examination and treatment methods, and highlight the problems in relevant clinical practice.

Foveation dynamics in congenital nystagmus IV: vergence.

PURPOSE: To evaluate foveation dynamics and characteristics of vergence eye movements during fixation of static targets at different distances and while tracking a target moving in depth in a subject with congenital nystagmus (CN). METHOD: Eye movements of a well-studied subject with CN were recorded using the magnetic search coil technique and analyzed using the OMtools software, including the eXpanded Nystagmus Acuity Function (NAFX). RESULTS: Both the phase planes and NAFX values during fixation of targets at various near distances were equivalent to those during fixation of a far target. When applied to vergence data, the NAFX values ("binocular" NAFX) were higher than for the individual eye data. Vergence tracking of targets moving in depth was demonstrated and was accurate for targets moving at speeds up to ~ 35°/sec. CONCLUSIONS: Target foveation qualities during fixation of targets at various near distances were equivalent to that during fixation of a far target. Stereo discrimination was limited by the foveation quality of the eye with the higher NAFX waveform. Foveation period slopes during vergence tracking demonstrated vergence movements despite the ongoing CN oscillation. Similar to what we found with fixation, pursuit, and the vestibulo-ocular systems, these findings establish that vergence in both static and dynamic viewing conditions functions normally in the presence of the CN oscillation.

Correlation between electroretinography, foveal anatomy and visual acuity in albinism.

BACKGROUND: Albinism patients have poor visual acuity in addition to hypopigmentation. Their foveal anatomy is abnormal, but correlation with function is incompletely understood. This study correlates retinal electrophysiology, visual acuity and optical coherence tomography (OCT) anatomy in albinism patients and compares with age-similar controls. METHODS: Institutional Review Board approval was obtained (IRB# 201408782). Patients were recruited from clinical practice. Inclusion criteria were at least three clinical features of albinism including iris transillumination, nystagmus, fundus hypopigmentation, or foveal hypoplasia on OCT and/or molecular genetic confirmation. Diagnosys (Lowell, Mass) full-field ERG (ffERG) and VERIS multifocal ERG (mfERG; Electro-Diagnostic Imaging, Milpitas, California) were obtained using standard International Society for Clinical Electrophysiology of Vision protocols. The mfERG protocol was a 4-min 103-hexagon protocol covering approximately 40° in diameter of central retina. Control subjects without albinism were recruited by in-hospital notices and invitations in clinic. OCT central thickness was recorded, and an OCT foveal score was calculated. Nonparametric permutation testing was utilized to determine the statistical significance. RESULTS: A total of 16 albinism patients and 19 age-similar controls were recruited. Four of 16 albinism patients had no nystagmus. Seventeen non-albinism controls had no ocular disorder other than refractive error. Two controls had infantile nystagmus with normal maculas on OCT. There was no statistically significant difference in mfERG amplitude or latency between albinism patients with or without nystagmus (lowest p = 0.68; 0.54, respectively). mfERG: 12 of 16 (75%) albinism patients had average ring 1 amplitudes within one standard deviation of controls despite having abnormal foveal anatomy on OCT. Patients averaged shorter latencies in rings 1 and 2 than controls (p = 0.005, p = 0.02). Patients averaged higher amplitudes than controls in rings 4, 5 and 6 (p = 0.03, p = 0.006, p = 0.004). There was no significant correlation between visual acuity and mfERG amplitudes in any ring (smallest p = 0.15). ffERG: Patients averaged higher amplitudes on 30 Hz flicker (p = 0.008). In all conditions, albinism patients had higher amplitude a-waves (p ≤ 0.03). B-waves were higher amplitude than controls in light-adapted 3.0 (p = 0.03). There was no statistical correlation between ffERG amplitudes and visual acuity (smallest p = 0.45). OCT: In albinism patients, thicker central macula on OCT correlated with lower mfERG amplitudes in all rings except for ring 1 (p < 0.05) and lower ffERG a-wave amplitudes on dark-adapted 0.01 (p = 0.003). Macular thickness on OCT did not correlate with visual acuity (p = 0.51); OCT foveal score did (p = 0.0004). CONCLUSIONS: Amplitude of mfERG does not correlate with visual acuity in any ring in patients with albinism. The slope of the change in amplitude from central to peripheral rings on the mferg is significantly different in albinism patients versus controls whether or not nystagmus is present. The decreased slope of change in amplitudes from center to periphery of the macula in albinism patients indicates changes in macular topography that are more important to visual deficits than the foveal depression.

Longitudinal Studies and Eye-Movement-Based Treatments of Infantile Nystagmus Syndrome: Estimated and Measured Therapeutic Improvements in Three Complex Cases.

INTRODUCTION AND PURPOSE: To demonstrate the utility of using eye-movement data to reveal the diagnostic characteristics of infantile nystagmus syndrome (INS), determine treatment, and both estimate and document therapeutic improvements in three patients with well-developed foveation periods, fairly broad, lateral gaze "nulls," head turns, strabismus, and complex, multiplanar nystagmus. PATIENTS AND METHODS: Infrared reflection, magnetic search coil, and high-speed digital video systems were used to record the eye movements of INS patients, pre- and post-Kestenbaum null-point correction surgery (horizontal or vertical). Data were analyzed and estimations made, using the eXpanded Nystagmus Acuity Function (NAFX) that is part of the OMtools toolbox for MATLAB. RESULTS: In all three subjects (S1-S3), both peak NAFX and longest foveation domain (LFD) improved from their pre-Kestenbaum values. S1: 0.700-0.745 (6.4%) and 25-34° (36%), respectively. S2: 0.445-0.633 (42.4%) and >40° to >50° (10%), respectively. S3: 0.250-0.300 (20%) and 13° to ≫18° (see text), respectively. CONCLUSIONS: S1: Even at the high ends of the pre-therapy NAFX and LFD spectra, INS foveation (and therefore, visual-function) improvements may be adequate to justify nystagmus surgery and provide clinical improvements beneficial to the patient. S2: INS foveation improvements in the vertical plane are equal to those originally estimated using the horizontal data in prior patients. S3: Two apparent NAFX peaks can be converted into a very broad peak by surgery based on the preferred lower peak.

Spontaneous Nystagmus in the Dark in an Infantile Nystagmus Patient May Represent Negative Optokinetic Afternystagmus.

Abnormal projection of the optic nerves to the wrong cerebral hemisphere transforms the optokinetic system from its usual negative feedback loop to a positive feedback loop with characteristic ocular motor instabilities including directional reversal of the optokinetic nystagmus (OKN) and spontaneous nystagmus, which are common features of infantile nystagmus syndrome (INS). Visual input plays a critical role in INS linked to an underlying optic nerve misprojection such as that often seen in albinism. However, spontaneous nystagmus often continues in darkness, making the visual, sensory-driven etiology questionable. We propose that sensorimotor adaptation during the constant nystagmus of patients in the light could account for continuing nystagmus in the dark. The OKN is a stereotyped reflexive eye movement in response to motion in the surround and serves to stabilize the visual image on the retina, allowing high resolution vision. Robust negative optokinetic afternystagmus (negative OKAN), referring to the continuous nystagmus in the dark with opposite beating direction of the preceding OKN, has been identified in various non-foveated animals. In humans, a robust afternystagmus in the same direction as previous smooth-pursuit movements (the eye's continuous tracking and foveation of a moving target) induced by visual stimuli has been known to commonly mask negative OKAN. Some INS patients are often associated with ocular hypopigmentation, foveal hypoplasia, and compromised smooth pursuit. We identified an INS case with negative OKAN in the dark, in contrast to the positive afternystagmus in healthy subjects. We hypothesize that spontaneous nystagmus in the dark in INS patients may be attributable to sensory adaptation in the optokinetic system after a sustained period of spontaneous nystagmus with directional visual input in light.

The effects of topical carbonic anhydrase inhibitor in treatment of nystagmus.

OBJECTIVE: To evaluate the effects of topical carbonic anhydrase inhibitor (CAI), brinzolamide (Azopt), for treatment of nystagmus patients. MATERIALS AND METHODS: Patients who used Brinzolamide for treatment of nystagmus were retrospectively analyzed. 23 patients were included in this study. The patients' diagnosis were idiopathic infantile nystagmus 18 (78.2%) and oculocutaneous albinism in 5 (21.8%). Azopt eye drop was used in both eyes, 3 times a day. Detailed eye examination in all of the patients before treatment and repeated at the end of the first week after treatment. SPSS 16.0 computer program was used for evaluation of DATAs. RESULTS: The mean follow-up was 32 ± 28 months. 23 patients 15 (65.2%) were male and 8 (34.7%) were female and the mean age was 12.6 ± 5.5. Before the management of topical brinzolamide, abnormal head position (AHP) were observed in 18 patients. After that we found reduction of nystagmus in 5 (22.7%) of the patients, increase in vision in 9 (40.9%) and reduced AHP in 18.3%. There is no identified change in 4 (18.1%). CONCLUSION: The medical treatment of nystagmus with topical brinzolamide was found effective in our series but, wider series and longer follow-up studies are needed.

[Nystagmus. Clinical characteristics and therapeutic options]. / Nystagmus. Klinische Charakteristika, therapeutische Optionen.

This article presents an overview of the pathophysiology of nystagmus and the differential diagnostics of congenital and acquired nystagmus. In addition, the principles of conservative, surgical and pharmacotherapy treatment options are described. The pathophysiological basis of nystagmus deepens the understanding of the etiology of the individual forms of nystagmus. The therapeutic approach to calming of nystagmus aims at an extension of the foveation time, which has the most significant impact on visual acuity. In congenital nystagmus this can be carried out by optimization of the retinal image, prisms or by bilateral surgical muscle repositioning to use the phenomenon of a null or neutral zone. In acquired nystagmus the off-label use of centrally acting medications can sometimes be helpful to calm the nystagmus and the associated oscillopsia.

Caracterización medicoquirúrgica en el síndrome de nistagmos infantil / Medical and surgical characterization of infantile nystagmus syndrome

Introducción: las oscilaciones oculares involuntarias en la infancia pueden comprometer la agudeza visual del niño; de ahí la importancia de manejarlas adecuadamente. Objetivo: describir el tipo de nistagmos y el tratamiento indicado en cada paciente con síndrome de nistagmos infantil. Métodos: se realizó un estudio observacional, descriptivo, de corte transversal, de una serie de 60 pacientes con diagnóstico síndrome de nistagmos infantil. Se analizaron la edad, los tipos de nistagmos, los defectos refractivos asociados y los tratamientos indicados en cada caso. Se procesaron con el programa informático para análisis estadístico SPSS para Window, versión 2.1, y se utilizó la media y la mediana como medidas de tendencia central, y la desviación estándar y el rango intercuartílico como medidas de dispersión. Resultados: la edad promedio de los pacientes estudiados fue de 5,8 años. Predominaron los pacientes del sexo masculino (56,7 por ciento vs. 43,3 por ciento). El nistagmos sensorial fue el encontrado con mayor frecuencia (80,0 por ciento) y la mediana fue de 4 años 6 meses. La causa más frecuente de este tipo de nistagmos fue la hipoplasia papilar (20,8 por ciento), en uno y otro sexos. El astigmatismo hipermetrópico fue el defecto refractivo hallado con mayor frecuencia en estos pacientes. El tratamiento farmacológico fue el más utilizado (65,0 por ciento), en particular con dorzolamida 2 porciento colirio (94,9 por ciento). El tratamiento quirúrgico se empleó en el 20,0 por ciento de los pacientes y la técnica más empleada fue la recesión de los 4 rectos horizontales.Conclusiones: los nistagmos sensoriales son los más frecuentes y se manejan fundamentalmente con tratamiento farmacológico(AU)

Introduction: the involuntary eye movements in childhood may compromise the child´s visual acuity; hence it is important to properly manage them.Objectives: to describe the type of nystagmus and the prescribed treatment for each patient suffering the infantile nystagmus syndrome. Methods: observational, descriptive and cross-sectional study conducted in 60 patients with diagnosis of infantile nystagmus syndrome. Age, types of nystagmus, associated refractive defects and prescribed treatments in each case were analyzed and processed with statistical analysis software SPSS for Windows, version 2.1. Mean and median; and standard deviation and interquartile range were used as central tendency and as dispersion measures, respectively. Results: the average age of the studied patients was 5,8 years. Men predominated (56,7 percent vs. 43,3 percent). The sensorial nystagmus was the most frequent (80 percent) and the median was 4 years and 6 months. The most common cause in this nystagmus type was papillary hypoplasia (20,8 percent) in both sexes. The hypermetropic astigmatism was the most found refractive defect in these patients. The drug treatment was the most used (65 percent), particularly 2 percent dorzolamide eyedrop (94,9 percent). The surgical treatment was used in 20 percent of the patients and the most used technique was recession of the 4 horizontal rectus muscle. Conclusions: sensorial nystagmus is the most frequent and they are fundamentally managed with drug treatment(AU)

Caracterización medicoquirúrgica en el síndrome de nistagmos infantil / Medical and surgical characterization of infantile nystagmus syndrome

Introducción: las oscilaciones oculares involuntarias en la infancia pueden comprometer la agudeza visual del niño; de ahí la importancia de manejarlas adecuadamente. Objetivo: describir el tipo de nistagmos y el tratamiento indicado en cada paciente con síndrome de nistagmos infantil. Métodos: se realizó un estudio observacional, descriptivo, de corte transversal, de una serie de 60 pacientes con diagnóstico síndrome de nistagmos infantil. Se analizaron la edad, los tipos de nistagmos, los defectos refractivos asociados y los tratamientos indicados en cada caso. Se procesaron con el programa informático para análisis estadístico SPSS para Window, versión 2.1, y se utilizó la media y la mediana como medidas de tendencia central, y la desviación estándar y el rango intercuartílico como medidas de dispersión. Resultados: la edad promedio de los pacientes estudiados fue de 5,8 años. Predominaron los pacientes del sexo masculino (56,7 por ciento vs. 43,3 por ciento). El nistagmos sensorial fue el encontrado con mayor frecuencia (80,0 por ciento) y la mediana fue de 4 años 6 meses. La causa más frecuente de este tipo de nistagmos fue la hipoplasia papilar (20,8 por ciento), en uno y otro sexos. El astigmatismo hipermetrópico fue el defecto refractivo hallado con mayor frecuencia en estos pacientes. El tratamiento farmacológico fue el más utilizado (65,0 por ciento), en particular con dorzolamida 2 por ciento colirio (94,9 por ciento). El tratamiento quirúrgico se empleó en el 20,0 por ciento de los pacientes y la técnica más empleada fue la recesión de los 4 rectos horizontales. Conclusiones: los nistagmos sensoriales son los más frecuentes y se manejan fundamentalmente con tratamiento farmacológico(AU)

Introduction: the involuntary eye movements in childhood may compromise the child´s visual acuity; hence it is important to properly manage them. Objectives: to describe the type of nystagmus and the prescribed treatment for each patient suffering the infantile nystagmus syndrome. Methods: observational, descriptive and cross-sectional study conducted in 60 patients with diagnosis of infantile nystagmus syndrome. Age, types of nystagmus, associated refractive defects and prescribed treatments in each case were analyzed and processed with statistical analysis software SPSS for Windows, version 2.1. Mean and median; and standard deviation and interquartile range were used as central tendency and as dispersion measures, respectively. Results: the average age of the studied patients was 5,8 years. Men predominated (56,7 percent vs. 43,3 percent). The sensorial nystagmus was the most frequent (80 percent) and the median was 4 years and 6 months. The most common cause in this nystagmus type was papillary hypoplasia (20,8 percent) in both sexes. The hypermetropic astigmatism was the most found refractive defect in these patients. The drug treatment was the most used (65 percent), particularly 2 percent dorzolamide eyedrop (94,9 percent). The surgical treatment was used in 20 percent of the patients and the most used technique was recession of the 4 horizontal rectus muscle. Conclusions: sensorial nystagmus is the most frequent and they are fundamentally managed with drug treatment(AU)

Nystagmus in pediatric patients: interventions and patient-focused perspectives.

Nystagmus refers to involuntary, typically conjugate, often rhythmic oscillations of the eyes. The most common cause of nystagmus in children is infantile nystagmus syndrome (INS). INS presents within the first few months of life and is sometimes accompanied by an ocular condition associated with sensory impairment. Because this condition affects a person throughout life, it is important to understand the options available to manage it. This review focuses on the underlying nystagmus etiology, psychosocial and functional effects of nystagmus, as well as current principles of management, including optical, pharmacological, surgical, and rehabilitative options. Currently, the neural mechanisms underlying INS are not fully understood. Treatment options are designed to increase foveation duration or correct anomalous head postures; however, evidence is limited to mainly pre- and post-study designs with few objective comparisons of treatment strategies. Management of INS should be individualized. The decision on which treatment is best suited for a particular patient lies with the patient and his/her physician.

Infantile nystagmus syndrome is associated with inefficiency of goal-directed hand movements.

PURPOSE: The effect of infantile nystagmus syndrome (INS) on the efficiency of goal-directed hand movements was examined. METHODS: We recruited 37 children with INS and 65 control subjects with normal vision, aged 4 to 8 years. Participants performed horizontally-oriented, goal-directed cylinder displacements as if they displaced a low-vision aid. The first 10 movements of 20 back-and-forth displacements in a trial were performed between two visually presented target areas, and the second 10 between remembered target locations (not visible). Motor performance was examined in terms of movement time, endpoint accuracy, and a harmonicity index reflecting energetic efficiency. RESULTS: Compared to the control group, the children with INS performed the cylinder displacements more slowly (using more time), less accurately (specifically in small-amplitude movements), and with less harmonic acceleration profiles. Their poor visual acuity proved to correlate with slower and less accurate movements, but did not correlate with harmonicity. When moving between remembered target locations, the performance of children with INS was less accurate than that of the children with normal vision. In both groups, movement speed and harmonicity increased with age to a similar extent. CONCLUSIONS: Collectively, the findings suggest that, in addition to the visuospatial homing-in problems associated with the syndrome, INS is associated with inefficiency of goal-directed hand movements. ( http://www.trialregister.nl number, NTR2380.).

Long-term results of four horizontal rectus muscle recession in nystagmus treatment.

PURPOSE: To report the long-term results of four horizontal rectus muscle recessions that were performed for infantile nystagmus syndrome treatment. METHODS: In this case series, patients with infantile nystagmus syndrome who had four horizontal muscle recessions previously were recruited and ophthalmological examination and electronystagmography recordings were performed. Objectively, amplitude and frequency of nystagmus were measured from the recordings and the intensity was calculated. Visual acuity, stereopsis, and alignment were evaluated and compared with the preoperative and postoperative values. RESULTS: The records of the 12 patients who had four horizontal rectus muscle recession surgery were evaluated and six patients (5 male, 1 female) who had regular follow-ups were included in this study. Mean follow-up was 14.17 ± 0.41 years (minimum 14 years, maximum 15 years) and mean age of patients at the last visit was 22 years (20-28 years). On subjective evaluation, two-thirds (4/6) of the patients were satisfied with the surgical results and had the impression that after surgery, nystagmus decreased in intensity and head posture improved. On objective evaluation, visual acuity was found to be the same, however, stereopsis improved (preoperatively and postoperatively median stereopsis was 600 sec arc vs 200 sec arc final). The decrease in nystagmus amplitude and frequency was still maintained. CONCLUSIONS: Nystagmus surgery on four horizontal rectus muscles has positive effects on binocular function and nystagmus parameters in the long-term follow-up. As we could not treat the primary pathology, the visual acuity was about the same but the decrease in nystagmus amplitude and frequency was still maintained with better stereopsis, and patient satisfaction.

Human parallels to experimental myopia? A literature review on visual deprivation.

Raviola and Wiesel's monkey eyelid suture studies of the 1970s laid the cornerstone for the experimental myopia science undertaken since then. The aim has been to clarify the basic humoral and neuronal mechanisms behind induced myopization, its eye tissue transmitters in particular. Besides acquiring new and basic knowledge, the practical object of the research is to reduce the burden of human myopia around the world. Acquisition and cost of optical correction is one issue, but associated morbidity counts more, with its global load of myopia-associated visual loss and blindness. The object of the present PubMed literature-based review is to evaluate apparent similarities between experience from disturbed imaging in experimental laboratory science and varieties within the spectrum of childhood human myopia. So far, the main impression is that macroscopical optical deprivation appears absent in the prevalent types of human myopia, nor is myopia a regular sequel where early eye pathology has led to poor imaging and optical deprivation. Optical aberrations of a higher order are a relatively new issue in myopia research, and microstructural deprivation is only marginally dealt within the survey. Links between experimental and human myopia appear mainly occasional, and with only few examples in humans where factual parallels appear credible. Clinical and epidemiological data on refraction remain important, in particular with a view to life style and environmental factors. Such knowledge may further serve as inspiration to the laboratory research, which aims at solving the basic enigmas on a tissue level.

Positive or negative feedback of optokinetic signals: degree of the misrouted optic flow determines system dynamics of human ocular motor behavior.

PURPOSE: The optokinetic system in healthy humans is a negative-feedback system that stabilizes gaze: slow-phase eye movements (i.e., the output signal) minimize retinal slip (i.e., the error signal). A positive-feedback optokinetic system may exist due to the misrouting of optic fibers. Previous studies have shown that, in a zebrafish mutant with a high degree of the misrouting, the optokinetic response (OKR) is reversed. As a result, slow-phase eye movements amplify retinal slip, forming a positive-feedback optokinetic loop. The positive-feedback optokinetic system cannot stabilize gaze, thus leading to spontaneous eye oscillations (SEOs). Because the misrouting in human patients (e.g., with a condition of albinism or achiasmia) is partial, both positive- and negative-feedback loops co-exist. How this co-existence affects human ocular motor behavior remains unclear. METHODS: We presented a visual environment consisting of two stimuli in different parts of the visual field to healthy subjects. One mimicked positive-feedback optokinetic signals and the other preserved negative-feedback optokinetic signals. By changing the ratio and position of the visual field of these visual stimuli, various optic nerve misrouting patterns were simulated. Eye-movement responses to stationary and moving stimuli were measured and compared with computer simulations. The SEOs were correlated with the magnitude of the virtual positive-feedback optokinetic effect. RESULTS: We found a correlation among the simulated misrouting, the corresponding OKR, and the SEOs in humans. The proportion of the simulated misrouting needed to be greater than 50% to reverse the OKR and at least greater than or equal to 70% to evoke SEOs. Once the SEOs were evoked, the magnitude positively correlated to the strength of the positive-feedback OKR. CONCLUSIONS: This study provides a mechanism of how the misrouting of optic fibers in humans could lead to SEOs, offering a possible explanation for a subtype of infantile nystagmus syndrome (INS).